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The George Washington Bridge is a double-decked suspension bridge that connects the New York City borough of Manhattan with New Jersey across the Hudson River. It is believed to be the world's busiest motor vehicle bridge, carrying over 103 million vehicles in 2016 – over 280,000 vehicles per day, and over twice as many axle loads, each impacting on the expansion joints that facilitate the superstructure’s movements.
The bridge was built between 1927 and 1931 to a design by the renowned Swiss-American civil engineer Othmar Ammann, who also designed two other iconic bridges in New York for which mageba has previously supplied expansion joints – the Verrazano Narrows Bridge and the Bayonne Bridge. Faced with the need to replace the structure’s “original style” finger-type expansion joints with devices of a similar design – tailored to precisely suit the existing structure in every dimension – the responsible engineers did not have to look far to find a supplier that could be relied upon to meet the project’s special requirements. Having successfully designed and manufactured the similar old finger-type joints of the Verrazano Narrows Bridge in 2015 - 2016, mageba had already proven its capabilities in providing such products and services on a nearby structure. In fact, with longitudinal movements of 2,700 mm (approx. 9 ft) at each end, the Verrazano Narrows Bridge project presented an even greater challenge than the George Washington Bridge with its expansion joint movements of up to 1,320 mm (52 inches). In both cases, due to the great length of the individual fingers needed to accommodate these large movements, the joints are designed to receive intermediate support at mid-span. Apart from that, the design and fabrication of the joints is based on two standard joint types from mageba’s current range, the TENSA-FINGER Type RSFD cantilever finger joint and the TENSA-FINGER Type GF sliding finger joint – both of which were used in the construction in 2010 of the Audubon Bridge over the Mississippi in Louisiana.
In total, mageba is supplying eight sliding finger joints, each weighing up to 156,000 pounds (71 tons), complete with the substructures that connect them to the bridge. Full assembly in the factory and delivery to site in lengths of up to two bridge lanes enables installation to be carried out as quickly as possible, with disruption to traffic kept to an absolute minimum on this critical structure.
The key factor on this project is reliability – with respect to the accuracy of the special tailored design and fabrication, to the on-time delivery of the manufactured products, and to the excellent long-term performance of the expansion joints in service. We like to think that mageba expansion joints are not just reliable – they are “George Washington Bridge reliable”!
Bridge designer: Othmar Ammann
Contractor: El Sol / GCCMOM JV
Owner: Port Authority of New York and New Jersey